Hepatocyte Diagram Style Evolution of Circulatory Systems

Biological diagram infographic titled "Evolution of Circulatory Systems" centered on a clean labeled evolutionary tree diagram showing major stages in the development of circulatory systems across animal groups, with branching lineage structure from simplest to most specialized forms. Place 5 labeled nodes around the central tree with thin leader lines, each containing a short English label and a one-line English function description. Use biologically accurate comparative anatomy and physiology, suitable for high school / general audience. Labels to include: "No circulatory system" — "Relies on diffusion to move gases and nutrients directly between cells."; "Gastrovascular cavity" — "Distributes digested nutrients through a central internal cavity in simple animals."; "Open circulatory system" — "Hemolymph leaves vessels and bathes organs directly in the body cavity."; "Closed circulatory system" — "Blood remains inside vessels for faster, more efficient transport."; "Double circulation" — "Separates pulmonary and systemic flow to improve oxygen delivery in vertebrates." Arrange the branches clearly from basal animals to advanced vertebrates, with subtle directional visual flow from early to later evolutionary forms. Include simple representative silhouettes or schematic organisms near each branch: sponge-like form, cnidarian body plan, arthropod or mollusk, annelid or fish, and amphibian/bird/mammal-style vertebrate circulation schematic. Add a small legend for vessel color coding: red for oxygenated pathway, blue for deoxygenated pathway, neutral gray for ancestral/simple forms. Visual style: modern textbook, vibrant educational primary palette, bright reds, blues, yellows, and greens with balanced white background, friendly academic mood, crisp typography, sharp readable labels, medical-textbook clarity, editorial scientific illustration, vector-clean lines, no photographic textures. All text MUST be written in English (array). Every heading, label, caption, legend and metric name in the image must be in English — not English. Spell each English word correctly using English characters and diacritics. Numbers stay as digits, no graphic gore, no real patient photos, no watermarks No graphic medical gore, no real patient photographs, no surgical blood. For human anatomy, keep illustrations educationally tasteful. For animal anatomy, no cruelty imagery. Scientifically accurate labeling and proportions.